X = pencils, y = pens
8x + 6y = 8.50
4x + 4y = 5.....multiply by -2
----------------
8x + 6y = 8.50
-8x - 8y = -10 (result of multiplying by -2)
-----------------add
-2y = - 1.50
y = -1.50 / -2
y = 0.75 <=== pens cost 0.75
4x + 4y = 5
4x + 4(0.75) = 5
4x + 3 = 5
4x = 5 - 3
4x = 2
x = 2/4
x = 0.50 <== pencils cost 0.50
Answer:



Step-by-step explanation:
Required
Which equals 

Collect like terms


Divide both sides by 2


Collect like terms


Divide both sides by 2


Collect like terms


Divide both sides by -2


Divide both sides by 2

Collect like terms



Divide both sides by 2

Collect like terms


Hence, the equations with the required solution are:



Answer:
m<D = 14
Step-by-step explanation:
Exterior angles thm:
83 + 6x - 4 = 21x + 4
6x + 79 = 21x + 4
6x - 21x = 4 - 79
-15x = -75
x = 5
m<D:
6x - 4
6(3) - 4
18 - 4
14